Publication :


Experimental analysis on the coupled effect between thermo-optical properties and microstructure of semi-crystalline thermoplastics

Authors: S. Boztepe, O. De Almeida, Y. Le Maoult and F. Schmidt
Year: juillet 2016
Conference : 32nd International Conference of the POLYMER PROCESSING SOCIETY.

Heating stage of the thermoforming of thermoplastics are critical as it has great effect on their formability under forming and therefore product quality. In order to optimize the thermoforming process of thermoplastics great attention is needed to be given for predicting the temperature profile on the heated sheets. As radiation heat transfer is widely used for the heating of thermoplastic preforms, physical background of the radiation heating of bulk thermoplastic polymers has to be understood well for an accurate prediction on their temperature profile. In the past, many numerical approaches were developed based on thermo-optical characteristics of thermoplastics whereas little attention was given to the relation between their microstructure and thermo-optical parameters. Considering semi-crystalline thermoplastics, the effect of microcrystalline structure is key to identify the thermo-optical properties and therefore to develop an accurate numerical radiative heat transfer model for optimization of thermoforming process. In our previous study [1], it was shown that there is a strong coupling between microcrystalline structure of highly crystalline polyolefin (PO) based polymer and its thermo-optical properties in the near-infrared (NIR) spectral region. In case of building an advanced radiative heat transfer model for IR heating assisted thermoforming processes of semi-crystalline thermoplastics this coupled effect cannot be neglected. In the present work, the relation between thermo-optical characteristics and microstructure of highly crystalline PO was extended considering the change in its morphology at various temperatures. The optical characteristics of the PO polymer were experimentally analyzed under heating conditions using an in-house developed device that is built using a Fourier Transform Infrared (FT-IR) spectroscopy, integrating sphere and heating plate. Thanks to the analyses, the change in the thermo-optical properties of the PO polymer were correlated to its varying morphology under increasing temperature. As semi-crystalline thermoplastics are heated up to melting temperature to soften enough for a successful forming process, their microcrystalline structure may show variation above glass transition temperature (Tg). Therefore, it is crucial to characterize temperature dependent relation between the morphology and thermo-optical characteristics of semi-crystalline polymers in relation to developing an accurate numerical model for IR-heating assisted thermoforming processes.

Bibtex citation :
Author={Boztepe, S. and De Almeida, O. and Le Maoult, Y. and Schmidt, F.},
Title={Experimental analysis on the coupled effect between thermo-optical properties and microstructure of semi-crystalline thermoplastics},
Booktitle={32nd International Conference of the POLYMER PROCESSING SOCIETY},

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